Process of producing arsenic compounds



1,624,281 P Y E. R. RUSH-TON PROCESS OF PRODUCING ARSENIC COMPOUNDS Filed May 28. 1924 [age/7e R Pas/1722a Patented Apr, 12, 1927.-

UNITED STATES EUGENE B. BUSHTON, OF MADISON, WISCONSIN.

PROCESS OF PRODUCING ABSENIC COMPOUNDS.

Application and my as,

The present invention has to do with a new and improved process of producing arsenic compounds, and particularly those militates against their use, because of the prohibitive cost of the product. It is my object to provide a process for the production of such compounds which will efliciently and cheaply give a product having all of the properties necessary to a satisfactory insecticide.

I have discovered that when a material, such as, for example, an oxide of an alkaline earth, is treated with gaseous arsenic trioxide, in the presence of heat and air, that a very complete and rapid combination of the elements necessary to form a satisfactory arsenate results.

While primarily intended to produce a cheap and eflicicnt insecticide, it is obvious that this is only one of the use; to which the product maybe put, and this specific ap plication of the arsenate is not, of'course,

to be taken as in any way limiting my invention, which, as stated, relates to a process of production of the arsenate.

In the drawing herewith is shown diagrammatically a laboratory apparatus by which the process has been Successfully carried out.

by burners 12. The neck 13 of the flask receives the end of a retort 14: suitably sup ported, and preferably, although not neces-.

:arily, so arranged that it may be revolved by any suitable drive mechanism, a drivingpulley being shown at one end o.t -th'e retort, and supporting roller being conventionally shown at each end of the retort. The retort H will be charged witlrthe suhstance to be acted on which may be any suitable metal compound of a group including oxides, hydroxides and carbonates, indicated at B, and l have found that calcium oxide is satisfactory, although it is obvious that any oxide,

hydroxide or carbonate ot' the alkali metals,

or alkali earth metals, might be used, cal- 1924. Serial No. 716,441.

cium oxide being given as one substance which I have used with success. I

The retort 14 will be heated in any suitable manner to redness, or to a temperature substantially between 500 C. and 1000 C., the present illustration showing conventionally a battery burner 16 to externally fire the retort i The delivery end of the retort enters the neck 17 of a container or flask 18 immersed, as here shown, in an oil bath 19, and the vapors coming from the retort and carryin the gases evolved are delivered to the necl of the flask 18.

- In order that the product of the process may be carried continuously through the apparatus, I provide a take-off tube 20, which may be connected with any suitable draft inducing means, and, atthe opposite end of the retort, I may provide an intake tube 21 so that when the apparatus is functioning, there will be a continuous draft through the retort with air going in through the intake pipe 21, and passing out the takeout pipe 20. This'pipe 21 enters the oil bath where it is'heated by contact with the oil and as a. consequence, air passing through said pipe is likewise heated. g

It will be observed that" the neck 13 of the container, or flask 10, at the intake end of the retort, is slightly spaced from the walls of the revolving retort, and the draft through the apparatus will induce the flow of a thin film of air at the receiving end of the retort, and, being counter to any pres; sures created in the retort, will prevent the escape of gas at the receiving end.

At the delivery end of the retort, it will beobserved that a similar arrangement is provided, the retort end projecting into the neck 5 17 of the container or flask 18, and being slightly separated therefrom, so that the draft through the take-out pi e 20 will create a flow of air in the form 0 a thin film "between the neck 17 of the flask and the de- 1 livery end of the retort, and that any back pressure and escape of gas will be avoided? I have-discovered that in the case of cal cium oxide, and oxides, hydroxides and carbonates of the other alkali metals and alkali earth fnetals, that, following my process, there results a; rapid combination of the oxide and the arsenic trioxide gas generated in container 10. The result of this combination seems to be an oxidation of the arsenic trioxide to form tri-calcium-orthoarsenate.

, The equation is represented by the following The reaction is best obtained at a temperature between 500 C. and 1000 C. and is rapid and complete, as has been ascertained by observing the relativel small amount of arsenic trioxide carrie oil in the air stream through the take-out pipe 20. The

container or flask 18 is intended more particularly to collect any efiluent gases,'such as uncombined arsenic trioxide, or any of the arsenate which may be entrained in the air stream.

Such product as has been collected in the flask 18, after a retort charge has been subjected to the process, may, of course, be removed therefrom.

In the practice of my process, I have found that it is practicable to calcine limestone directly in the retort 13 to produce the calcium oxide, and in the commercial development of my invention, this might be advantagbous, as it would eliminate the step of first calcining limestone, where calcium oxide is the substance used, and then charging it into the retort. A mixture of arsenic trioxide gas and air may be introduced during the calciningoperation so that the procspecified, since it obviously ess ma be continuous and while the oxide forme by the calcination is still hot.

As stated, substances other than calcium oxide may be used, in fact, any metals which will combine with the gaseous arsenic trioxide, and particularly an oxide, hydroxide and carbonate of the alkali metal or of the alkali earth metals. For example, potassium oxide, sodium oxide, magnesium oxide, strontium oxide, and barium oxide, and their hydroxides and carbonates are substances which might be substituted in carrying out In process, and there may, of course, be ot ers. I do not, therefore, limit my invention to the particular substances herein may be practiced with any product, for example, the oxides, hydroxides and carbonates of such 'metals as=zinc and load, without changing the principles of the present invention.

The arsenic trioxide maybe. obtained in any suitable manner, but I have found that by oxidizing calcium arsenite, calcium arsenate'and arsenic trioxide is produced, and

the trioxide may be recovered and utilized in my process. I have found that at relatively lowv temperatures, for example 360 0., arsenic trioxidevapor reacts with 'calcium oxide to form calcium 'aG'senite.

The latter is not oxidized to calcium arsenate evenin the presence of an excess of air at th s temperature. However, if the temperasubstance with which arsenic tri-- oxide Wlll combine to produce the desired ture is raised to a red heat, or to temperature between 500 C. and 1000 C. in contact with air, some of the arsenic trioxide is driven off as a vapor and combines with the lime and oxygen to form calcium arsenate. My process is equally efiicient when this step is employed 7 The manner of practicing the process will, it is believed, be clear, and, obviously, it is extremely simple. The container or flask 18, is charged with arsenic trioxide, or white oxide, and vaporized. The resulting gaseous arsenic trioxide passes to the rotating retort 14c which has been charged with cal..- cium oxide, or in which limestone has, by the heat of the burners, been converted into calcium oxide. The gaseous arsenic trioxide is brought into intimate contact with the agitated mass of calcium oxide in the retort, and rapidly and effectively combines to form the arsenate. The air draft or suction through the apparatus carries off the uncombined'product, and it may be collected in any suitable form of apparatus.

It will be obvious that my illustration to show the steps of my process is simply conventional, and it is not to be taken as restrictive. Various types of apparatus may be used, and a retort inclined to the horizontal and provided with proper feed and discharge devices could be used,so thatthe chanic, or chemist, may be made and still be within the range of my invention.

In order that the process maybe more easily, understood by reference to the drawing, the arsenic trioxid or other arsenic compound is indicated at A. The calcium oxide or substance to be reacted upon is indicated at B. The air stream, as indicated by the arrow, enters through the pipe 21,

which is heated by contact With the oil bath, thus preheating the air, and draws the vapors from the chamber 10 to the right into the retort 14, which is preferably rotated and. which contains the substance The air stream containing the arsenica-l vapor Will react with thesuio' such as calcium oxide,.and .a relatively long stance in the kiln,

kiln or tube is employed in order that the reaction may be complete. The temperature is preferably between 500 .C..a nd"10)0 (3., and; the tube is continuouslyrotated, The air stream passes out through the opposite end of the retort and carries with it'the uncombined gases. Soiiieof theefliuen'tgproducts, however, pass into the chamber 18 and are condensed and recovered, such products being shown at C.- The arsenate formed re-. mains in the retort and may be removed as desired. The retort may be so arranged as to deliver the a'rsenateas, formed and the process therefor made continuous.

It will be understood that in the roasting of arseniferous ores, the arsenical gases generated may be embodied -in the process of this invention. In such a,case, the arsenical gases are passed from the roasting kiln into relation with the oxide, hydroxide or carbonate, and the reaction occurs in the same manner as set forth heretofore. That} is to say, an air stream carries the arsenical vapors into contact with the reaction substance in identically the same manner described herein. 1

I claim:

N 1. The process which consists in subject- Ill) 7. The process of subjecting metal comrouuds'which include oxides. hydroxides,

and carbonates to the action of arsenical va-- ing a substance contributing to the formation of an arsenic compound to an ar:enical gas in the presence of oxygen and heat.

2. The process which consists in subjecting a substance contributing to theformation of an arsenic coinpound to an arsenical gas in the presence of oxygen and at a temperature between 500 C. and 1000 C.

3. The process which consi:ts in subjecting a substance contributing to the formation of an arsenic compound to an arsenical hydroxides and carbonates, to the action of arsenical vapor in the presence of heat and air. n 1

6. The process of subjecting one of a group of metal compounds which include oxides,

hydroxides, and carbonates tothe action of arscnicalvapor in the presence oifair and at a temperature between 500 C. and

por in the presence of air and at a temperatu re between 500 C. and 1000 (1., and agitating the mass. j

8. The process of subjecting one of a group of compounds of an alkali forming met-a1 which includes oxides, hydroxides and carbonates to the action of arsenical Va,-

por in the presence of heat and .air.

in the presence of air anda't a temperature substantially 500 C. to1000 C.

10. The process of subjecting one of a contributing to the formation of an arsenic compound to the action of a heated air stream containing an arsenical gas. v

12. The process of subjecting one of a group of metal compounds which includes oxides, hydroxides and carbonates to the action of a heated air stream containing arsenical gas.

13. The process of subjecting one of. a group of compounds of an alkali formingmetal WlllChlllClllClGs oxides, hydroxides and carbonates to the action of a heated. air

stream containing an arscnical gas.

14. The process which consists in reacting upon one of a group of metal compounds whichincludes oxides, hydroxides, and carbonates with arsenical vapors generated by the roasting of arseniferous ores in the pres ence of heat and air.

15. The process which consists in reacting upon one of a group of metal compounds which includes oxides, hydroxides'and car bonates with arsenical vapors generated by the roasting of arsenical ores, such vapors being drawn in an air stream and reaction taking place at a temperature of substantially 500 C. to 1000 C. r 16. The process which consists in react- .lill) ing upon one of a group of metal compounds which includes oxides, hydroxides and car bonates with arsenical vapors generated by the roasting of arsenical ores, such vapors being drawn in a heated air stream and, re-

action taking place at a temperature of substantially 500 C. to 1000 C., and agitating the mass.

upon one of a group of compounds of an alkali forming metal which includes oxides,

. hydroxides and carbonates witli arsenical 17. The process which consists in reacting vapors generated by the roasting of arseniterous ores in the presence of heat andair.

, 18. The process which consists inreact-- ing upon one of a group of compounds of an ,alkali forming metal which includes oxides. hydroxides and carbonates with 'arsenical lvapors generated by the roasting of arse-v ,niferous ores, such vapors being entrained in an air stream and reaction taking place at atemperature of substantially 500 C. to

119; The process which consists infreacting upon one of a group of compounds of analkali forming-metal which includes oxides, I

hydroxides and carbonates-with arscnical val l I o pors generated by the roasting of arseniferous ores, such vapors being entrained in a heated air stream and reaction taklng place in'the presence of air with the mass at red heat and with agitation;

20.'The process of reacting upon one of a group of compounds which includes oxides, hydroxides and carbonates with arsenical vapors, ,the combination taking place throughout a prolonged period in the pres ence of heat and air.

21. The process of reacting upon one of a group of metal compounds which include oxides. hydroxides and carbonates with arsenical vapors, the combination taking place through a prolonged period in the presence of air and at a temperature, of substantially group of metal compounds which include oxides. hydroxides and carbonates with arsenical vapors entrained in an air stream, the combination taking place through a prolonged period in' the presence oi heat and air.

25. The process of acting upon one of a group of metal compounds which include oxides, hydroxides and carbonates with arsenical vapors entrained in an air stream, the combination taking place through a prolonged period in the presence of heat and air, and with agitation of the mass.

26. The process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to the action of an arsenical gas in the presence of heat and air.

27. The process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to the action of an arsenical gas in the presence of heat an air and agitating the mass.

28. The process of subjecting calcium compounds of the group which includes oxides, hydroxides and carbonates to the action of an air stream containing arsenical gas in the presence of heat and air. v

29. The process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to the action of an arsenical gas in the presence of air and at a temperature of between 500 C. to 1000 C.

30. The process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to the action of an arsenical gas in the presence of air and at a temperature of between 500 C. and 1000 (1., and agitating the mass.

31. The process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to gaseous arsenic trioxide in the presence of heat and air.

32. The-process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to an air stream containing gaseous arsenic trioxide in the presence of heat and air.

33. The process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to the action of an air stream containing gaseous arsenic trioxide, the reaction taking place through a prolonged period, and in the presence of oxygen and heat.

34. The process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to gaseous arsenic trioxide in the presence of air andcat red heat.

35. The process of subjecting calcium compounds of the group which include oxides, hydroxides and carbonates to gaseous arsenic trioxide in the presence of air and at red heat and agitating the mass.

36. The process which consists in subjecting calcium compounds which include oxides, hydroxides and carbonates to the action of gaseous arsenic trioxide in the presence of heat and air while the mass is being agitated.

37. The process which consists in calcining a carbonate and subjecting the hot mass to an arsenical vapor in the presence of air.

38. The process which consists in calcining a metal carbonate and subjecting the hot mass to an air stream containing arsenic trioxide at a temperature of substantially 500 C. to 1000 C. while agitating the mass.

39. The process which consists in calcining a carbonate of an alkali forming metal and subjecting the mass at red heat to an arsenical vapor in the presence of air.

40. The process whichconsists in calcining an alkali forming metal and subjecting the hot mass .to an air stream containing arsenic trioxide at a temperature of sub stantially 500 C. to 1000 (1, and agitating the mass.

41. The process which consists in subjecting calcium compounds of a group which includes oxides, hydroxides and-carbonates to the action of an air stream containing arsenical vapors produced in the roasting of arseniferous ores at a temperature of substantially 500 C. to 1000 C.

42. The process which consists in calcining a carbonate and passing an air stream contannng arsenlcal vaporsproduced from the roasting of arsemferous ores over the cal lcined carbonate, and maintaining the mass agitated at a temperature between 500 C. and 1000 C. a

43. The process which consists in subjecting calcium compounds of'a group which include hydroxides, carbonates and oxides to the action of a heated air stream containing arsenical vapors at a temperature of. substantially 500 C. to 1000 C.

44. The process of forming arsenates which consists in reacting upon calcium oxide in after subjecting the mass to temperatures between 500 C. and 1000 C. in the presence pf air.

45. The process of producing calcium arsenate which consists in subjecting calcium oxide while in a state of agitation to the action of arsenic trioxide in the presence of.

.oxygen and heat.

In testimony-whereof I have hereunto set my hand.

EUGENE R. RUSHTON. 

